Gas purge valve

ABSTRACT

A gas purge valve comprising a housing ( 12 ) formed with an inlet ( 24 ) and an outlet ( 30 ) formed with a valve seating ( 54 ), and a sealing assembly ( 38 ) comprising a sealing member ( 70 ) displaceable between an open position and a closed position. The sealing assembly ( 38 ) is supported by an external support lever ( 42 ) mechanism extending outside the housing ( 12 ), to thereby displace the sealing assembly ( 38 ) into sealing engagement with the valve seating at the closed position.

FIELD OF THE INVENTION

The present invention generally relates to fluid flow valves and isparticularly, but not exclusively, concerned with such valves which aredesigned to serve as gas discharge valves or gas purge valves.

BACKGROUND OF THE INVENTION

Air purge valves are designed to be installed in liquid flow systemssuch as, for example, water main distribution lines or sewage collectionsystems, or liquid tanks, and are intended to discharge air (typicallyin water supply systems) or other gasses (e.g. in sewage systems orthick liquid supply systems), thus avoiding the formation andaccumulation of gas pockets and bubbles which interfere with the liquidflow and which can also damage accessories and components of the liquidsystem. On the other hand, when the liquid system is drained, it isrequired to air the lines so as to avoid their collapse under rapidvacuum build-up.

A basic requirement for gas purge valves is their ability to effectivelyand rapidly discharge both large and small quantities of gas whilst, atthe same time, being or becoming sealed against liquid discharge.Conventional air purge valves are formed with a gas discharge outletthrough which the gases are discharged, but which become sealed againstliquid discharge by a float located in a valve housing and which becomespressed against the outlet so as to seal it with a rising level ofliquid in the valve housing.

Such valves, when provided with a relatively small discharge outlet areeffective for the discharge of small quantities of gas, but cannot copewhen large quantities have to be discharged. Where, however, in order torender the valve capable of handling large quantities of gas it isprovided with a large discharge outlet (and, consequently, a largedimensioned float), problems arise in ensuring that the valve canreadily and rapidly discharge relatively small quantities of gas afterthe discharge outlet has been sealed against liquid outflow. Thus, oncethe valve housing is filled with liquid and the float has been pressedagainst the relatively large outlet so as to seal it, the valve willonly reopen once the pressure in the housing has dropped to atmosphericpressure and, as a consequence, such a valve cannot be used for thecontinuous venting of relatively small amounts of air.

Moreover, such valves have the drawback of being substantially sensitiveto the presence of dirt, grit, etc., particularly where manufacturingtolerances or erosion of various components, built-up of dirt or scale,etc., greatly influence the behavior of the float and its response tochanges of the fluid flowing therethrough (liquid or gas). Thus, theperformance of such air purge valves is somewhat deficient and they maymalfunction.

A large variety of gas valves have been proposed for gas purge valvescapable of effectively and rapidly discharging both relatively small andlarge quantities of gas. Such a proposal is to be found in U.S. Pat.Nos. 4,770,201 and 6,105,608. Prior art arrangements, whilst allowingfor the effective and speedy opening of the outlet aperture for rapiddischarge of relatively small quantities of gas as well as its completeopening for the discharge of large quantities, are neverthelessvulnerable in particular when installed in lines through which dirtflows along with the liquid, e.g. sewage lines.

However, in valves of the type comprising a float member received withinthe valve housing and being articulated with an outlet sealing means,there is provided some guidance to facilitate regular and smoothdisplacement of the sealing means. For that purpose it has beensuggested to provide a support rod coaxially extending with the sealingmeans and axially displaceable within an external support bushing. Thisarrangement however is prone to malfunctioning upon deformation of thesupport rod and upon entering of dirt to the vicinity of the bushing.Even more so, the axial guidance does not assist in displacement of thesealing means, but rather may cause an obstacle to normal operationthereof.

SUMMARY OF THE INVENTION

It is thus an object of the present invention to provide a gas purgevalve in which the sealing member is externally guided so that the valvewill operate trouble-free also under extreme dirt conditions.

According to the present disclosed technology there is provided a gaspurge valve comprising a housing formed with an inlet and an outlet,said outlet formed in turn with a valve seating, and a sealing assemblycomprising a sealing member displaceable between an open position and aclosed position; wherein the sealing assembly is supported by anexternal support lever (pivotable support arm) mechanism, i.e. extendingoutside said housing, to thereby displace the sealing assembly intosealing engagement with said valve seating at the closed position.

According to a particular design of the present invention the gas purgevalve comprises a housing fitted with an inlet being in flowcommunication with a float chamber within the housing, and an outletformed at an upper end thereof; a sealing assembly for sealing saidoutlet, and a float disposed within said float chamber articulated tothe sealing assembly; said sealing assembly being carried at a first endof an external support lever having a second end thereof pivotallyattached to the housing.

The float member is directly or indirectly articulated to the sealingassembly. According to one arrangement the float is coupled to thesealing assembly by a rigid link and according to another embodiment thelink is flexible (e.g. a cord, etc.) or comprises one or more rigidlinks with at least one degree of freedom. According to a differentarrangement, the float is directly articulated to the sealing assemblyor to a component associated therewith.

Furthermore, the support lever may be received within a water-tightcasing, wherein the casing is received within an outlet duct extendingfrom the valve outlet and being in flow communication therewith.

According to an improved modification of the invention, the valve outletis of the combined type comprising a major, kinetic outlet for high flowrate gas flow, and an auxiliary, automatic outlet for low flow rate gasflow. By a particular design, the auxiliary outlet comprises an apertureadjoined by an auxiliary valve seating, said auxiliary outlet aperturebeing substantially smaller in area than the major outlet aperture; aflexible closure membrane secured at one end to the sealing member ofthe major outlet and adapted to be biased against said auxiliary valveseating so as to seal said auxiliary outlet aperture; the float memberbeing articulated to an opposite end of said membrane.

By one particular design, the auxiliary valve seating has asubstantially elongated slit-like shape, communicating at one endthereof with the major outlet aperture.

The support lever can be provided with arrangements for altering themoment of rotation about a pivoted end thereof and/or may comprisedampening arrangements.

According to one particular embodiment, the support lever is pre-loadedin either or both directions. In one sense, the support lever may bebiased in a direction so as to open the valve (i.e. to disengage thesealing assembly from the valve seating) so as to reduce or preventhammering. Biasing the support lever in an opposite sense, i.e. intoengagement with the valve seating of the sealing assembly, entails tightsealing. This pre-loading may be adjustable.

By a specific arrangement, the pre-loading mechanism comprises an axleattached to the lever and received within a casing fixedly supported bythe housing, a coiled spring having one end thereof engaged with saidaxle and an opposed end thereof engaged with a tension setting nutrotatable with respect to said axle in a first sense to tension thespring, and in an opposite sense to loosen the spring. Otherarrangements may include provision of various types of springs,dampeners, balance-weights, dynamic weights (e.g. water weight, etc.).

By one particular application, the valve according to the invention isused in conjunction with a sewage system.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carriedout in practice, some embodiments will now be described, by way ofnon-limiting examples only, with reference to the accompanying drawings,in which:

FIGS. 1A and 1B illustrate a gas purge valve according to a firstembodiment of the present invention, wherein:

FIG. 1A is an isometric view of the valve in a closed position; and

FIG. 1B is a sectional isometric view of the valve in its open position;

FIGS. 2A and 2B illustrate a top portion of the valve of FIG. 1 in itsclosed position, in an isometric view and in a sectioned view,respectively;

FIGS. 3A and 3B illustrate the valve of FIGS. 1A and 1B in its partiallyopen (automatic) position, in a sectioned view and in an isometricsectioned view, respectively;

FIGS. 4A and 4B illustrate the valve of FIGS. 1A and 1B in its fullyopen (kinetic) position, in a sectioned view and in an isometricsectioned view, respectively;

FIGS. 5A and 5B illustrate a gas purge valve according to a secondembodiment of the present invention, wherein:

FIG. 5A is a side view of the valve, and

FIG. 5B is a longitudinal sectioned, mirror image, of the valve of FIG.5A;

FIGS. 6A to 6C are sectional views through a top portion of the valve ofFIGS. 5A and 5B, illustrating the sealing portion in a closed position,a partially open (automatic) position, and in a fully open (kinetic)position, respectively;

FIGS. 7A to 7D illustrate a biasing mechanism associated with thesupport lever of the valve according to the present invention, wherein:

FIG. 7A is an isometric view of the top region of the valve;

FIG. 7B is an isometric view of the biasing assembly in larger scale,its casing made translucent;

FIG. 7C is an isometric view of the biasing assembly detached from thevalve housing, its casing made translucent; and

FIG. 7D is a sectioned isometric view of the biasing assembly of FIG.7C;

FIG. 8A is a sectioned view of a gas purge valve according to anotherembodiment of the present invention, illustrated in a normally-closedposition; and

FIG. 8B is an enlargement of the top portion of the valve, in its closedposition.

DETAILED DESCRIPTION OF THE INVENTION

Attention is first directed to FIGS. 1A and 1B of the drawingsillustrating a gas purge valve in accordance with one embodiment of thepresent invention, generally designated 10, which in the present exampleis of the type fitted for cooperation with a sewage or waste line.

The valve 10 comprises a frustoconical (though other shapes are possibletoo) metal housing 12 comprising a base portion 14 and an upper portion16 secured to one another by a coupling flange 20. The housing 12 isformed with an inlet port 24 and comprises a base flange 26 forattaching the housing to the liquid line. An outlet port 30 is formed ata top cover member 32 flanged to the upper housing portion 16 by meansof articulating flange 34.

A sealing assembly, generally designated 38, extends within the housing12 and is articulated to an external support lever 42 as will beexplained in further detail herein below. Pivotally supported from thesealing assembly 38 there is a float member 46 (FIG. 1B) suspended by arigid connecting rod 48 pivotally secured to the sealing assembly 38.

However, it is appreciated that the float member 46 may be directly orindirectly articulated to the sealing assembly 38. According to otherembodiments (not shown) the link is flexible (e.g. a cord, etc) orcomprises one or more rigid links with at least one degree of freedom.According to a different arrangement (not shown) the float member 46 maybe directly articulated to components associated with the sealingassembly 38, e.g. support member 72 or pivot bar 80′ (FIG. 2B).

For better understanding the design of the valve outlet port 30 and thesealing assembly 38, further attention is directed to FIGS. 2A and 2B.The outlet port 30 comprises a circular major outlet 52 defining a majorvalve seating 54 and further comprising a slit-like auxiliary outlet 56having an auxiliary valve seating 58 (FIG. 2B).

The support lever 42 is pivotally secured at a first end thereof 60 to asupport extension 62 fixedly attached to the housing 12. A second end 64of the support lever 42 is articulated to the sealing assembly 38.

The sealing assembly 38 comprises a major sealing member 70 (e.g. madeof a resilient material) retained by a rigid support member 72 and isclamped by a top retaining member 74 whereby the sealing member 70 hasan exposed edge for sealingly bearing against the boundaries of themajor valve seating 54 (FIG. 2B). Sealing member 70 is integrally formedin the present example with a strip-like sealing membrane 78 having oneend thereof articulated to a free end of a pivot bar 80, the latterhaving an opposed end thereof pivotally secured at 82 to the supportmember 72. Connecting rod 48 of the float member 46 is pivotally securedat 86 to said pivot bar 80.

The valve 10 in accordance with the present invention has threeprinciple positions as illustrated in FIGS. 2, 3 and 4. The firstposition is illustrated in FIGS. 2A and 2B depicting the valve 10 in itsclosed position, wherein the sealing member 70 tightly bears against thevalve seating 54 of the major outlet 52 and similarly the strip-likesealing membrane 78 sealingly bears against the auxiliary valve seating58 of the auxiliary outlet 56. This position takes place when liquidenters the housing 12, applying buoyancy force on float member 46 whichby means of rod 48 ensures tight sealing engagement of the sealingmember 70 and the sealing membrane 78. It is to be appreciated that theauxiliary outlet 56 may be otherwise formed then a slit-like apertureand may adjoin the major outlet 52 rather than be bounded thereby. It isalso to be understood that the valve 10 may be a so-called kineticvalve, suited for gas flow at high flow rates and not comprising theso-called automatic portion, i.e. suited for low flow rate gas flow.

Turning now to FIGS. 3A and 3B, the valve 10 is illustrated in theso-called automatic position wherein the strip-like sealing membrane 78detaches from the auxiliary outlet 56 whilst the sealing member 70remains tightly engaged with the major valve seating 54. This situationoccurs while the float member 46 is only partially immersed in liquidwithin the housing 12. When the auxiliary outlet 56 is open, it issuitable for discharging gases from the valve also at significantly lowflow rate, also when the pressure within the housing 12 is high.

In the position illustrated in FIGS. 4A and 4B, the valve 10 is shown ina fully opened position, also referred to as a kinetic position, whereinthe sealing member 70 detaches from the major valve seating 54 in theabsence of liquid within the housing 12. The situation is useful forallowing air egress into the system, e.g. upon draining of the system.Alternatively, this position is useful when the system is filled with aliquid, in order to discharge large amounts of gas (typically air).

Of particular importance in the embodiment depicted in FIGS. 1 to 4 isthe externally extending support lever 42 which is not influenced byflow or pressure considerations occurring within the housing 12 and evenmore so, dirt typically flowing in such systems (in particular where thevalve 10 is used with a sewage system) does not affect the support ofthe sealing assembly 38 and proper sealing is obtained.

It is further appreciated that the float member 46 may be directlyarticulated to the sealing assembly 38, e.g. by omitting the connectingrod 48.

It is also noted that the external support lever 42 enables displacementof the sealing assembly 38 to significantly evacuate the housing 12 viathe outlet port 30 (FIG. 4B) to thereby facilitate gas flow at high flowrates.

Further attention is now directed to FIGS. 5 to 7 illustrating anotherembodiment of a valve in accordance with the present invention whereinlike components have been designated same reference numbers shifted by200.

Turning first to FIGS. 5A and 5B, there is illustrated a valve 210comprising a housing 212 having a frustoconical shape formed with aninlet port 224 and an outlet port 230 (FIG. 5B). The valve 210 is fittedwith a sealing assembly 238 from which a float member 246 is suspendedby means of a float connecting rod 248. It is further noted that thesealing assembly 238 (abutting a valve seating 254) is supported by anexternal support lever 242 pivotally secured at 260 via a pre-loadingmechanism 101 to a support extension 262 fixedly attached to the housing212. The particular design and purpose of the pre-loading mechanism 101will be apparent hereinafter by particular reference to FIGS. 7A to 7B.

It is further noted in FIGS. 5 and 6 that the external support lever 242extends through an outlet duct 106 extending from the outlet port 230 toan outlet opening 108. If desired, a screen may be fitted at the outletopening 108 (not shown) to prevent ingress of insects and tampering withthe sealing assembly 238 (e.g. in a water supply system).

With further attention now directed to FIGS. 6A-6C the valve 210 isillustrated in a completely closed position (FIG. 6A) where both themajor outlet 230 and the auxiliary outlet 256 are sealed. In theposition seen in FIG. 6B, the valve 210 is in its partially openposition wherein the major outlet 230 is sealed and the auxiliaryslit-like outlet 256 is open. In FIG. 6C both the major outlet 230 andthe auxiliary outlet 256 are fully open. These positions correspond withthe positions illustrated in FIGS. 2, 3 and 4, respectively.

As can further be noted in FIGS. 6A-6C, the float connecting rod 248 isloosely connected to a connecting bar 280 of the sealing assembly 238though there is provided a coiled spring 113 for dampening the directcoupling between the float member 246 and the sealing assembly 238 so asto minimize motion transfer from the float member to the sealingassembly during swinging and buoyant motion of the float member. Asalready mentioned, the float member 246 may be coupled to the sealingassembly 238 by other arrangements which mute the dangling motion of thefloat member.

Further attention is now directed to FIGS. 7A-7D illustrating thepre-loading mechanism 101 comprising a sealed casing 115 secured to thehousing 212 and to the support extension 262 (FIGS. 7A and 7B). Theexternal support lever 242 is formed with a pivot axle 119 coaxiallyreceived within the casing 115 wherein a coiled spring 121 has one endthereof 123 fixedly secured to the axle 119 (FIG. 7D) with its opposedend 125 fixedly received within a tension adjusting member 127 formedwith a hexagonal head 129 and where a set screw 131 projects through thecasing 115 for arresting the adjusting member 127 at any angularposition depending on the required damping force.

The arrangement is such that the support lever 242 is biased in adirection so as to displace the sealing assembly 238 into sealingengagement with the valve seating 254 whereby the valve 210 is suitablefor use in particular as an air inlet valve, i.e. useful when a fluidconduit is drained, etc. The support lever 242 may be pre-loaded in avariety of different ways, such as, for example, by weights (masselements or liquid within the housing 212), elastic biasing means,dynamic weights (e.g. liquid chambers), etc.

It is noted that is also possible to provide a suspending arrangementfor delaying motion of the sealing assembly 238 into the sealingposition. Such suspension may be obtained for example by providing aviscous or visco-elastic damping mechanism or elastic means, to therebysustain sealing engagement of the sealing assembly 238 with the valveseating 254, to thereby reduce or eliminate hammering. However, it is tobe appreciated that dampening means may be provided in addition orwithout pre-loading of the support lever 242, in any direction (i.e.closing or opening).

Further attention is now directed to FIGS. 8A and 8B of the drawings,directed to a modification of a valve according to the presentinvention, generally designated 300. The valve 300 is similar to thevalve of FIG. 1B, the major difference residing in that it does notcomprise a float member (46 in FIG. 1B) and in that the sealing assemblyis merely of the so-called kinetic type, i.e. adapted for gas flow athigh rates.

According to the embodiment of FIGS. 8A and 8B a housing 302 is formedwith an inlet 306 (not seen in FIG. 8B) and an outlet 308 formed in turnwith an outlet valve seating 312 (best seen in FIG. 8B). A sealingassembly generally designated 316 comprises a sealing member 318 (e.g.made of a resilient material) retained by a rigid support member 320 andis clamped by a top retaining member 322, whereby an exposed peripheralportion of the sealing member 318 is fitted for sealingly bearingagainst the boundaries of the valve seating 312.

Sealing member 318 is coupled to a pivotal arm/support lever 326, whichis pivotally secured at a first end thereof 328 to a support extension332 fixedly attached to the housing 302. According to the particularillustrated embodiment, the sealing assembly is rigidly linked to thesupport lever 326.

Support lever 326 is biased into a normally-closed position, e.g. by aspring (not seen), whereby the sealing assembly 316 is in sealingengagement with the valve seating 312. This structure provides a gasinlet valve, i.e. a valve admitting gas inlet into the valve housing 302e.g. upon draining of the line connected to the valve. As mentionedhereinabove, there may be provided various dampening means to reduce oreliminate hammering during operation of the valve 300.

Whilst several embodiments have been shown and described, it is to beunderstood that it is not intended thereby to limit the disclosure, butrather it is intended to cover all embodiments, modifications andarrangements falling within the spirit and the scope of the presentinvention, as defined in the appended claims, mutatis mutandis.

1. A gas purge valve comprising a housing fitted with an inlet being inflow communication with a float chamber within the housing, and anoutlet formed at an upper end thereof, said outlet formed with a valveseating, a sealing assembly disposed within said float chamber forsealing said outlet, and a float disposed within said float chamber andbeing pivotally attached to the sealing assembly by a rigid link; saidsealing assembly being carried at a first end of an external supportlever, the external support lever extending outside the housing andcomprising a second end pivotally attached to the housing at an outsideportion thereof allowing the sealing assembly freedom to self align withthe valve seating at a closed position.
 2. A gas purge valve comprising:a housing having a valve inlet and a valve outlet; a valve seatingdefined at said valve outlet; a sealing assembly comprising a sealingmember adapted for sealing engagement with said valve seating; a floatmember articulated to said sealing assembly within the housing, andbeing displaceable susceptive to liquid level within the housing; and anexternal support lever comprising a first end being internally receivedwithin the housing when in an open position, the first end beingarticulated to the sealing assembly, the external support leverextending outside the housing and comprising a second end pivotallyattached to the housing at an outside portion thereof, allowingdisplacement of the sealing assembly along a non-linear path between anopen position and said closed position, and allowing the sealingassembly freedom to self align with the valve seating at a closedposition.
 3. A gas purge valve comprising a housing formed with an inletand an outlet, said outlet formed with a valve seating, and a sealingassembly comprising a sealing member displaceable between an openposition and a closed position; the sealing assembly being internallyreceived within the housing, when in the open position; wherein thesealing assembly is supported by a first end of an external supportlever mechanism, the external support lever mechanism extending outsidesaid housing and comprising a second end pivotally attached to thehousing at an outside portion thereof to form a pivotal attachmenttherewith to thereby displace the sealing assembly into sealingengagement with said valve seating at the closed position, the pivotalattachment displacing the sealing assembly along a non-linear pathbetween said open position and said closed position, the gas purge valvefurther comprising a float member pivotally secured to said sealingassembly within the housing, and being displaceable susceptive to liquidlevel within the housing.
 4. The gas purge valve according to claim 3,wherein the support lever is provided with a pre-loading mechanism foradjusting the moment of rotation about a pivoted end thereof.
 5. The gaspurge valve according to claim 3, wherein the support lever is providedwith dampening arrangements to dampen displacement of the sealingassembly into the closed or open position.
 6. The gas purge valveaccording to claim 3, wherein the housing has a frustoconical shape. 7.The gas purge valve according to claim 3, comprising a casing fixedlysupported by the housing, wherein the casing is received within anoutlet duct extending from the valve outlet and being in flowcommunication therewith.
 8. The gas purge valve according to claim 3,for use in conjunction with a sewage system.
 9. The gas purge valveaccording to claim 3, wherein the support lever is coupled to thesealing assembly allowing freedom for the sealing assembly to self alignwith the valve seating at a closed position.
 10. The gas purge valveaccording to claim 3, wherein the float member is suspended from thesealing assembly.
 11. The gas purge valve according to claim 10, whereinthe float member is suspended from the sealing assembly by a rigidconnecting rod.
 12. The gas purge valve according to claim 11, whereinan end of the connecting rod is pivotally coupled to the sealingassembly.
 13. The gas purge valve according to claim 11, wherein theconnecting rod is spring-biased to dampen motion of the connecting rod.14. The gas purge valve according to claim 3, wherein the support leveris pre-loaded so as to effect engagement of the sealing assembly withthe valve seating.
 15. The gas purge according to claim 14, whereinpre-loading of the support lever is adjustable to thereby adjust theforce required for sealing the valve.
 16. The gas purge valve accordingto claim 3, wherein there is further provided a pre-loading mechanismfor pre-loading the support lever so as to adjust the moment about apivot end thereof.
 17. The gas purge valve according to claim 16,wherein the pre-loading mechanism comprises an axle attached to thesupport lever and received within a casing fixedly supported by thehousing, a coiled spring having one end thereof engaged with said axleand an opposed end thereof engaged with a tension setting nut rotatablewith respect to said axle in a first sense to tension the spring, and inan opposite sense to loosen the spring.
 18. The gas purge valveaccording to claim 17, wherein the tension setting nut is rotatablyfixable at different positions so as to allow for adjusting thepre-loading setting.
 19. The gas purge valve according to claim 18,wherein the casing of the pre-loading mechanism is water and dirtsealed.
 20. The gas purge valve according to claim 3, wherein thesupport lever is biased in a direction to displace the sealing assemblyinto sealing engagement with the valve seating.
 21. The gas purge valveaccording to claim 20, wherein the biasing force is adjustable.
 22. Thegas purge valve according to claim 3, wherein the valve outlet is of thecombined type comprising a major, kinetic outlet for high flow rate gasflow, and an auxiliary, automatic outlet for low flow rate gas flow. 23.The gas purge valve according to claim 22, wherein the auxiliary outletcomprises an aperture adjoined by an auxiliary valve seating, saidauxiliary outlet aperture being substantially less in area than themajor outlet aperture; a flexible closure membrane secured at one end tothe sealing member of the major outlet and adapted to be biased againstsaid auxiliary valve seating so as to seal said auxiliary outletaperture; the float member being articulated to an opposite end of saidmembrane.
 24. The gas purge valve according to claim 23, wherein theauxiliary valve seating has a substantially elongated slit-like shape,communicating at one end thereof with the major outlet aperture.
 25. Thegas purge valve according to claim 24, wherein the flexible closuremembrane adapted for sealing the auxiliary outlet aperture, isintegrally formed with the sealing member adapted for sealing the majorvalve outlet.
 26. The gas purge valve according to claim 24, wherein theopposite end of the closure membrane is articulated to one end of apivot bar pivotally secured at an opposed end thereof to the sealingmember of the major outlet, and articulated to the float member.
 27. Thegas purge valve according to claim 26, wherein the float member iscoupled to the pivot bar via a connecting member.
 28. The gas purgevalve according to claim 24, wherein the major outlet sealing member isretained by a support member whereby the sealing member has exposededges for bearing against the boundaries of the major valve seating. 29.The gas purge valve according to claim 28, wherein one face of theexposed edges bears against a bedding of the support member, whilst anopposite face thereof is fitted for sealing engagement with theboundaries of the major valve seating.
 30. The gas purge valve accordingto claim 3, wherein the valve outlet comprises first and second outletapertures respectively bounded by first and second valve seatings, saidfirst aperture being of substantially elongated slit like shape,communicating at one end thereof with the second outlet aperture andbeing substantially less in area than the second aperture; a flexibleclosure membrane secured at one end to a sealing member for said secondoutlet and adapted to be biased against said valve seatings so as toseal said outlet apertures; the float member being articulated to anopposite end of said membrane.
 31. The gas purge valve according toclaim 30, wherein the sealing assembly comprises a sealing member forsealing engagement with a seating of the major outlet, and a flexibleclosure membrane secured at one end to said sealing member and adaptedto be biased against a seating of the auxiliary valve outlet so as toseal said; an opposite end of said membrane being articulated to thefloat member.